Industry has long used self-contained bearing and housing units designed to support heavy rotating shafts. These bearing units require adequate lubrication for the bearings. The lubrication must be retained in the housing unit and in addition, contaminants such as debris, dirt, etc. must be kept out of the housing unit, out of the lubrication, and away from the bearing in order to ensure smooth operation. These self-contained units are commonly known as pillow blocks and/or plumber blocks. The types and sizes cover virtually all applications that employ the use of heavy, and sometimes long, shafts in equipment such as road building, conveyors, fans, etc.
In most cases, spherical roller bearings are employed in the housings or pillow blocks in order to accommodate angular and axial shaft displacement that results from loading and, in some cases, thermal growth of the shaft. The angular displacement of the shaft may also result when heavy radial loads are applied some axial distance from the bearing mounting position. In the normal pillow block, a small amount of angular misalignment to the shaft can be tolerated because of the spherical shape of the outside diametric surface of the bearing.
However, the seals associated with the pillow block have not been able to accommodate this angular displacement except by making the seal flexible and/or having a larger than desired amount of tolerance between the shaft and the sealing surface.
The normal, severe duty, pillow block is horizontally split, and the top half can be removed for convenient inspection and installation of the shaft, bearings, and seals. In the prior art, there have been many different systems for sealing split pillow blocks including lip seals, springs, V-rings, felt, grease pockets and relatively rotating rings forming a labyrinth seal sometimes called a disc pack.
These sealing devices and arrangements including combinations of the aforementioned systems have not been particularly successful because of misalignment between the seal and shaft. Constant maintenance and attention is required in order to ensure continued operation of the equipment (i.e. the shaft does not bind and/or seize).
All of the presently known means of sealing pillow blocks are ineffective because of the imperfect radial positioning of the sealing mechanisms or devices. The devices are ineffective and imperfectly positioned because of the non-concentricity of the housing and sealing mechanisms with respect to the bearing bore and shaft. All of the prior sealing mechanisms were affixed and positioned relative to the bearing housing and designed to permit or have a concentric offset to permit misalignment of the shaft with respect to the housing and/or the sealing device. The seals all were designed to accommodate the variance in the shaft angle, as noted before, either by making the contacting surfaces of material such as felt, etc. or having sufficient radial clearances between the sealing device and the housing to accommodate the variance in the angular displacement of the shaft.